High Side (HSD) power outputs are used to provide power to a load. A common problem when using HSD power outputs is the need of an external freewheeling diode to protect against the high energy inductive loads generate when these are switched off. In some examples, the inductive loads include either real inductive loads (e.g., wiper motors, washer motors, solenoids, relays, to mention a few examples) or long harnesses with significant inductivity (e.g., trailer outputs on commercial vehicles with harness length of more about 40 m).
Normally, HSD outputs cannot handle the high energy produced by inductive loads having either high currents (e.g., a short circuit of a trailer output) or high inductivity (e.g., high inductivity relay) or both (e.g., wiper motor in a stalled condition).
When freewheeling diodes are used in combination with HSD outputs one problem is normally the protection of the freewheeling diode and the HSD against reverse battery conditions (e.g., commercial vehicles can go down to approximately −36V). Several previous approaches exist to protect the freewheeling diode and the HSD, but none of these approaches provide sufficient protection against high current and high inductivity events (e.g., wiper motor in a stalled condition or trailer outputs being short circuited with a 40 m long harness (trailer outputs normally have high short circuit currents >200 A)).
The problems of previous approaches have resulted in some user dissatisfaction with these previous approaches.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity. It will further be appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. It will also be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein.